1. Field of the Invention
The present invention relates to a solid oxide fuel cell (SOFC) using a perovskite solid electrolyte.
2. Description of the Related Art
Generally, an SOFC is constituted of an air electrode (cathode), a fuel electrode (anode), and a solid oxide electrolyte provided between these two electrodes. Since a high-temperature condition is required to enable the solid oxide electrolyte to exhibit ion conductivity, the SOFC is operated at a high temperature of around 1000° C. or above. However, such a high temperature operational condition results in difficulties in securing operational stability and reliability for the SOFC. In addition, since materials to be used as peripheral parts must also have high-temperature resistance, material costs have been high. Due these circumstances, studies have been conducted into the development of a material, especially a solid oxide electrolytic material, to operate the SOFC at a much lower temperature.
A recently reported LaGa-based perovskite solid electrolyte represented by a composition formula of La1-xSrxGa1-yMgyO3-d (T. Ishihara et al; J. Am. Chem. Soc., 116, 3801-3803 (1994)) exhibits excellent oxygen ion conductivity at a low temperature, and therefore has attracted attention as an electrolytic material effective for achieving low-temperature operability of the SOFC. Japanese Laid Open Patent Publication Hei 9-161824 (published in 1997) discloses an SOFC using a LaGa-based electrolyte, both a fuel and an air electrode suitable for the SOFC, and a method for fabricating the SOFC.